1. Field of the Invention
The invention relates to a structure of partition wall for defining unit-light emitting areas in a surface discharge scheme AC type plasma display panel.
2. Description of the Related Art
Recent years, a plasma display panel of a surface discharge scheme AC type as an oversize and slim display for color screen has been received attention, which is becoming widely available.
FIGS. 9 to 13 schematically show the cell structure for the surface discharge scheme AC type plasma display panel which has been proposed by the present applicant. FIG. 9 is a front view of the cell structure. FIG. 10 is a sectional view taken along the V1xe2x80x94V1 line of FIG. 9. FIG. 11 is a sectional view taken along the V2xe2x80x94V2 line of FIG. 9. FIG. 12 is a sectional view taken along the W1xe2x80x94W1 line of FIG. 9. FIG. 13 is a sectional view taken along the W2xe2x80x94W2 line of FIG. 9.
In FIGS. 9 to 13, on the backside of a front glass substrate 1 to serve as a display screen of the plasma display panel (referred as xe2x80x9cPDPxe2x80x9d hereinafter), a plurality of row electrode pairs (x, Y) are arranged in parallel to extend in the row direction of the front glass substrate 1 (in the left-to-right direction of FIG. 9).
The row electrode X is composed of T-shaped transparent electrodes Xa formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and a bus electrode Xb which is formed of a metal film, extends in the row direction of the front glass substrate land connects to narrowed proximal ends of the transparent electrodes Xa.
Similarly, the row electrode Y is composed of T-shaped transparent electrodes Ya formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and a bus electrode Yb which is formed of a metal film, extends in the row direction of the front glass substrate 1 and connects to narrowed proximal ends of the transparent electrodes Ya.
The row electrodes X and Y are alternated on the front glass substrate 1 in the column direction (in the vertical direction of FIG. 9). The transparent electrodes Xa or Ya disposed along the bus electrodes Xb, Yb extend toward the corresponding row electrode X or Y such that the tops of the widened distal ends of the transparent electrodes Xa, Ya face each other to interpose a discharge gap g, having a predetermined width, between them.
Each of the bus electrodes Xb, Yb is formed in a double layer structure with a black conductive layer Xbxe2x80x2, Ybxe2x80x2 on the display surface side and a main conductive layer Xbxe2x80x3, Ybxe2x80x3 on the back surface side.
A dielectric layer 2 is formed further on the backside of the front glass substrate 1 to overlay the row electrode pairs (X, Y). Furthermore, on the backside of the dielectric layer 2, an additional dielectric layer 2A is formed in each position which opposes adjacent bus electrodes Xb and Yb of the two row electrode pairs (X, Y) adjacent to each other, and additionally which opposes an area between the adjacent bus electrodes Xb and Yb, to protrude from the backside of the dielectric layer 2 and to extend in parallel with the bus electrodes Xb, Yb.
On the backsides of the dielectric layer 2 and the additional dielectric layers 2A, a protective layer 3 made of MgO is formed.
Next, a back glass substrate 4 is arranged in parallel with the front glass substrate 1. On the front surface of the back glass substrate 4 facing toward the display surface, column electrodes D are disposed in parallel at regularly established intervals from each other to extend at positions, opposing the transparent electrodes Xa and Ya of the row electrode pairs (X, Y), in a direction orthogonal to the row electrode pair (X, Y) (the column direction).
A white dielectric layer 5 is further formed on the face of the back glass substrate 4 on the display surface side to overlay the column electrodes D.
On the dielectric layer 5, a plurality of partition walls 6 are disposed in the column direction regularly spaced from each other with an interstice SLxe2x80x2 extending in the row direction. The partition wall 6 is shaped in a ladder pattern by vertical walls 6a each extending in the column direction between the two column electrodes D arranged in parallel with each other, and transverse walls 6b each extending in the row direction in a position opposing each additional dielectric layer 2A. The ladder-patterned partition walls 6 define the space between the front glass substrate 1 and the back glass substrate 4 into areas opposing the paired transparent electrodes Xa and Ya of each row electrode pair (X, Y), to form a quadrangular discharge cell C in each area.
For providing the partition walls 6, a glass material layer of a predetermined thickness is formed on the dielectric layer 5 and undergoes a sandblast process to be cut through a mask having a predetermined pattern, and then the patterned glass material layer is burned.
A face of the vertical wall 6a of the partition wall 6 on the display surface side is out of contact with the protective layer 3 (see FIGS. 11, 12) to form a clearance r therebetween. On the other hand, a face of the transverse wall 6b on the display surface side is in contact with a portion of protective layer 3 overlaying the additional dielectric layer 2A (see FIGS. 10, 11) to shield the adjacent discharge spaces S from each other in the column direction.
On the five faces of a surface of the dielectric layer 5 and the side faces of the vertical walls 6a and the transverse walls 6b of the partition wall 6 facing each discharge space S, a phosphor layer 7 is formed to overlay all of the five faces.
Colors of the phosphor layers 7 are set in order of red, green and blue for the sequence of discharge spaces S in the row direction.
The inside of the discharge space S is filled with a discharge gas.
Between the front glass substrate 1 and the dielectric layer 2, a black light absorption layer 8 is formed at a position, which opposes the interstice SLxe2x80x2 between the adjacent partition walls 6 and which is situated between the back-to-back bus electrodes Xb and Yb of the respective row electrode pairs (X, Y) adjacent to each other in the column direction, to extend along the above bus electrodes Xb, Yb in the row direction. Furthermore, a light absorption layer 9 is formed at a position opposing the vertical wall 6a of the each partition wall 6.
In the above PDP, each row electrode pair (X, Y) makes up a display line (row) L on a matrix display screen, and each discharge space S defined by each ladder-patterned partition wall 6 forms a discharge cell C.
In the above PDP, an image is displayed as follows: first, through addressing operation, discharge is caused selectively between the row electrode pairs (X, Y) and the column electrodes D in the particular discharge cells C, to scatter lighted cells (the discharge cell C in which wall charge is formed on the dielectric layer 2) and nonlighted cells (the discharge cell C in which wall charge is not formed on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the addressing operation, in all the display lines L, the discharge sustain pulses are applied alternately to the row electrode pairs (X, Y) in unison, and thus surface discharge is produced in each lighted cell on every application of the discharge sustain pulse.
In this manner, the surface discharge in each lighted cell generates ultraviolet radiation, and thus the red, green and blue phosphor layers 7 particularly formed in the discharge cells C are selectively excited to emit light, resulting in forming the display screen.
The above PDP has a feature in that since each partition wall 6 defines the discharge cells C in a pattern in which parallel lines cross at right angles, and the transparent electrodes Xa, Ya of the row electrodes X, Y extend from the corresponding bus electrodes Xb, Yb toward each other to independently shape into an island-like form in each discharge cell C, even if each discharge cell is reduced in size to increase definition of a screen, there may not be occurrence of interference between the discharges of the adjacent discharge cells in the row direction.
The above PDP has another feature in that: it is possible to form each partition wall 6 in a ladder pattern independently for each row and thus forming the transverse wall 6b which is approximately equal in width to the vertical wall 6a. Therefore, when the partition walls 6 are burned, there is little difference in shrinkage produced during the burning between the vertical wall 6a and the transverse wall 6b. This results in preventing deformation of the discharge cells from being caused by a wrap in the front glass substrate 1 or the back glass substrate 4, damage of the partition wall 6, and so on.
However, when each partition wall 6 is formed in the ladder pattern as in the foregoing PDP, another disadvantage arises. That is to say, in burning the partition wall 6, each of the transverse walls 6b on both ladder-sides of the partition wall 6 are drawn inward by the shrinkage of the vertical walls 6a as illustrated in FIG. 14, and therefore an opposite side of the transverse wall 6b, which is opposite to a supported side by joining with the dielectric layer 5 (the upper side in FIG. 14) are mutually inclined inward.
For overcoming the disadvantage, if a width of the transverse wall 6b is designed to be larger than that of the vertical wall 6a, as described above, a difference in shrinkage caused by the burning may be produced between the vertical wall 6a and the transverse wall 6b to cause the deformation in the discharge cell C. Alternatively the shrinkage may cause a great tensile internal stress in the vertical wall 6a to cut the vertical wall 6a. 
Moreover, in the construction of the PDP as described above, the protective layer 3 overlaying the additional dielectric layer 2A is in contact with the transverse walls 6b of each partition wall 6 to completely shield the adjacent discharge cells C from each other in the column direction. The complete shielding does not fully provide the priming effect, which induces discharge between the adjacent discharge cells C, in the column direction. This increases a discharge delay time in selecting the discharge in the addressing operation when the image is formed. In order to prevent extension of the discharge delay time, if a drive pulse applied in the addressing operation for stabilizing the selective discharge increases in width, this produces another disadvantage in which the time required for the addressing operation is extended.
The present invention has been made to overcome the disadvantages associated with the surface discharge scheme AC type plasma display panel as described above.
It is therefore a first object of the present invention to prevent partition walls for defining unit light emitting areas (discharge cells) in a pattern, in which parallel lines cross at right angles, from being damaged and deforming in a forming process for the partition walls.
It is a second object of the present invention to make it possible to ensure priming effect even between unit light emitting areas (discharge cells) adjacent to each other in a column direction.
To attain the first object, a partition wall structure for a plasma display panel according to a first invention advantageously includes partition walls in order that a discharge space, which is formed between a front substrate and a back substrate of the plasma display panel including a plurality of row electrode pairs extending in a row direction and arranged on the front substrate in a column direction and a plurality of column electrodes extending in the column direction and arranged on the back substrate in the row direction, is defined in each intersecting position of the row electrode pair and the column electrode to form unit light emitting areas. Such partition wall includes a pair of transverse walls placed in parallel with each other having a space equal to the width of the unit light emitting area in the column direction, and vertical walls placed between the pair of transverse walls in parallel with each other having a space equal to the width of the unit light emitting area in the row direction and integrally coupled to the pair of transverse walls, to define the unit light emitting areas in each line of the plasma display panel. Further, the partition wall is formed to have a width of a portion of the transverse wall situated between the adjacent vertical walls in a parallel direction to the vertical wall, larger than a width of a portion of the transverse wall coupled to the vertical wall in the same direction.
With the partition wall structure for the plasma display panel according to the first invention, when the formation of partition walls is performed by burning a glass material layer which is formed in a required thickness and patterned, the transverse wall is formed such that its width of the portion situated between the adjacent vertical walls is lager than its width of the portion coupling to the vertical wall, to reinforce the portion situated between the adjacent vertical walls. Hence, the transverse wall has durability to withstand a tensile force produced by the shrinkage of the vertical wall in burning.
In consequence, according to the first invention, the transverse walls are prevented from deforming and being damaged when the partition walls are burned. The partition walls enable to define the unit light emitting areas in a desired shape.
To attain the first object, the partition wall structure for the plasma display panel according to a second invention features, in addition to the configuration of the first invention, in that the width of the portion of the transverse wall coupled to the vertical wall is formed to be approximately the same as a width of the vertical wall in a direction orthogonal to a longitudinal direction of the vertical wall.
According to the partition wall structure for the plasma display panel of the second invention, due to the approximately equal size in width between the portion of the transverse wall coupled to the vertical wall and the vertical wall, the tensile internal stress produced in the vertical wall by the shrinkage produced in burning is reduced. For this reason, the vertical wall is prevented from cutting and a shrinkage ratio is approximately equal between the vertical wall and the portion of the transverse wall coupled to the vertical wall, resulting in preventing the partition wall from being deformed by the shrinkage produced in burning.
To attain the second object, the partition wall structure for the plasma display panel according to a third invention features, in addition to the configuration of the first invention, in that a thickness of the portion of the transverse wall coupled to the vertical wall is formed to be smaller than a thickness of a portion of the transverse wall situated between the adjacent vertical walls to form a groove making communication between the inside and the outside of the transverse wall on the portion of the transverse wall coupled to the vertical wall.
According to the partition wall structure for the plasma display panel of the third invention, the partition walls are disposed in the discharge space between the front substrate and the back substrate of the plasma display panel while extending in the row direction and being arranged in parallel with each other with spacing at required intervals in the column direction. In this case, even when the transverse wall shields the back substrate from the front substrate, each unit light emitting area defined by the partition wall is communicated with the interstice, which is formed between the adjacent partition walls in the column direction, via the groove formed on the portion of the transverse wall coupled to the vertical wall.
In consequence, even when the transverse wall of the partition wall shields the adjacent unit light emitting areas from each other in the column direction, priming particles (a pilot flame) which are produced by the discharge in the interstice between the adjacent transverse walls associated with the discharge caused in the unit light emitting area, are scattered via the groove into an adjacent unit light emitting area in the column direction to induce the discharge, resulting in ensuring the priming effect between the adjacent unit light emitting areas in the column direction.
To attain the first object, a partition wall structure for a plasma display panel according to a fourth invention advantageously includes partition walls in order to define a discharge space, which is formed between a front substrate and a back substrate of the plasma display panel including a plurality of row electrode pairs extending in a row direction and arranged on the front substrate in a column direction and a plurality of column electrodes extending in the column direction and arranged on the back substrate in the row direction, in each intersecting position of the row electrode pair and the column electrode to form unit light emitting areas. Such partition wall includes a pair of transverse walls placed in parallel with each other having a space equal to a width of the unit light emitting area in the column direction, and vertical walls placed between the pair of transverse walls in parallel with each other having a space equal to a width of the unit light emitting area in the row direction and integrally coupled to the pair of transverse walls, to define the unit light emitting areas in each line of the plasma display panel. The partition walls defining the unit light emitting areas in each line are arranged in parallel with each other, to face a portion of the transverse wall coupled to the vertical wall toward a corresponding portion of a transverse wall coupled to a vertical wall of an adjacent partition wall with spacing at a required interval, and to form a portion of the transverse wall situated between the adjacent vertical walls integrally with a corresponding portion of a transverse wall situated between adjacent vertical walls of an adjacent partition wall.
With the partition wall structure for the plasma display panel according to the fourth invention, when the formation of partition walls is performed by burning a glass material layer which is formed in a required thickness and patterned, the transverse wall is formed such that its width of the portion situated between the adjacent vertical walls is lager than its width of the portion coupled to the vertical wall, to reinforce the portion situated between the adjacent vertical walls. Hence, the transverse wall has durability to withstand a tensile force produced by the shrinkage of the vertical wall in burning.
In consequence, according to the fourth invention, the transverse walls are prevented from deforming and being damaged when the partition walls are burned. The partition walls enable to define the unit light emitting areas in a desired shape.
To attain the first object, the partition wall structure for the plasma display panel according to a fifth invention features, in addition to the configuration of the fourth invention, in that the width of the portion of the transverse wall coupled to the vertical wall is formed to be approximately the same as a width of the vertical wall in a direction orthogonal to a longitudinal direction of the vertical wall.
According to the partition wall structure for the plasma display panel of the fifth invention, since the transverse wall is formed such that the width of the portion coupled to the vertical wall is approximately equal to the width in the direction orthogonal to the longitudinal direction of the vertical wall, the tensile internal stress produced in the vertical wall by the shrinkage produced in burning is reduced. For this reason, the vertical wall is prevented from cutting and a shrinkage ratio is approximately equal between the vertical wall and the portion of the transverse wall coupled to the vertical wall, resulting in preventing the partition wall from being deformed by the shrinkage produced in burning.
To attain the second object, the partition wall structure for the plasma display panel according to a sixth invention features, in addition to the configuration of the fourth invention, in that a thickness of the portion of the transverse wall coupled to the vertical wall is formed to be smaller than a thickness of a portion of the transverse wall situated between the adjacent vertical walls to form a groove on the portion coupled to the vertical wall for making communication between the unit light emitting area defined by the partition wall and an interstice formed between the adjacent partition walls.
According to the partition wall structure for the plasma display panel of the sixth invention, the partition walls are disposed in the discharge space between the front substrate and the back substrate of the plasma display panel with the transverse walls thereof being oriented in the row direction. In this event, even when the transverse wall of the partition wall shields the back substrate from the front substrate, each unit light emitting area defined by the partition wall is communicated with the interstice, which is formed between the adjacent transverse walls in the column direction, via the groove formed on the portion of the transverse wall coupling to the vertical wall.
In consequence, even when the transverse wall of the partition wall shields the adjacent unit light emitting areas from each other in the column direction, priming particles (a pilot flame), which are produced by the discharge in the interstice between the transverse walls associated with the discharge caused in the unit light emitting area, are scattered via the groove into an adjacent unit light emitting area in the column direction to induce the discharge, resulting in ensuring the priming effect between the adjacent unit light emitting areas in the column direction.
These and other objects and advantages of the present invention will become obvious to those skilled in the art upon review of the following description, the accompanying drawings and appended claims.